Last summer’s Supreme Court decisions on same sex marriage created a sea change for gay couples, but the details of that change depend on where they got married, where they live now and the federal agencies involved.

The changes are dramatic and complex enough that financial advisors should contact any clients with same sex partners to discuss the implications, planner Thomas Tillery explained at the AICPA’s financial planning conference in Las Vegas on Monday.

Tillery is a longtime fee-only planner with a string of credentials—CFP, CLU, ChFC, LUTCF, CRPC—as well as a masters of science in financial services and, interestingly, a masters of arts in Christian education from the Southern Baptist Theological Seminary. What Tillery doesn’t have is much patience for advisors who ignore these issues because they disagree with the Supremes’ decisions; they’re “fools,” he said, who need to understand the new realities and serve their clients appropriately.

Here’s a brief summary of what advisors and couples need to know, by agency:

The IRS. Same sex couples are considered legally married for federal income tax purposes if they were wed in a state that recognizes their marriage. It doesn’t matter whether the state where they currently reside recognizes such unions, Tillery said. Couples can apply for refunds for up to three years’ worth of tax returns if they were married during those years and their newly-recognized status would have resulted in lower taxes. Some gay couples had to pay income tax on health insurance benefits for their spouse; the elimination of that requirement could mean money back from the government.

Social Security. Here, residence matters: if the state where couple applies for benefits recognizes same sex marriage, then Social Security spousal and survivor benefits are available to that couple. One way around this limitation is for the couple to establish residency in a state that recognizes their marriage and then apply for benefits. They could later move to a state that doesn’t recognize their marriage without risking the loss of their Social Security benefits, Tillery said.

Department of Defense. Benefits are available for same sex spouses who can show a valid marriage license from any state or country that recognizes gay marriage. The state where the couple currently lives is irrelevant. Service members can get special leave to travel to a state where same sex marriage is recognized in order to wed.

Department of Labor/ERISA. Qualified pension plans have guaranteed protections for spouses, including automatic survivor benefits unless the spouse waives them and provisions that allow for division of retirement assets at divorce without triggering tax bills. Whether a same-sex married partner qualifies as a spouse for these provisions depends on whether the state where the employee resides recognizes same sex marriage.

The Supreme Court decisions have implications for other aspects of a couple’s financial life, including estate planning, family leaves, participation in flexible spending accounts and more.

My advice: if you don’t have an advisor who can help you with these issues, find one who can. It could make a huge difference in your financial lives and financial security.